[russelluresti]

Historically speaking, unions do not form until the workers are in a crunch/threatened with losing their jobs. During these times, things are good for most developers so they don't see the need to unionize.

Unions are also only effective because they are generally location-based. If you want to build a building in New York, you have to get a construction crew that can work in New York. That makes it very easy for a group to unionize New York workers - because their tools for bargaining (e.g. strikes) are easy to carry out when centralized. But on the web, this is much more difficult. If you unionized all U.S. developers, companies would simply outsource to other countries where the union doesn't exist. And while there are a few international unions, AFAIK none of them are very effective at organizing. In short, digital work is very easy to outsource and makes unions completely ineffectual.